Field of the Invention
The present invention relates to a polymer compound and a negative resist composition, particularly a negative resist composition using a polymer compound that has a polarity inversion function used for processing a semiconductor substrate or a photomask substrate, and also relates to a laminate and a patterning process using the same, and a compound.
Description of the Related Art
It is well known that a finer pattern rule is required for LSI with higher integration and higher processing speed. Exposure methods and resist compositions significantly vary accordingly. Especially in lithography of a 0.2-μm or less pattern, KrF excimer laser beam, ArF excimer laser beam, electron beam, or the like is used as the exposure light source, and a chemically amplified resist composition having a good sensitivity to such high energy beams and a high resolution is used as the photoresist composition.
The resist composition can be classified into a positive type, in which an exposed part dissolves, and a negative type, in which an exposed part remains as a pattern. The more useful one is selected according to a resist pattern to be required. A chemically amplified negative resist composition generally contains a polymer that can dissolve in an aqueous alkaline developer, an acid generator that can decompose by photo-exposure and generate acid, and a crosslinking agent that can crosslink the polymer by using the acid as a catalyst and then insolubilize the polymer in the developer (the polymer and the crosslinking agent can be integrated). In addition, a basic compound for controlling diffusion of the acid generated by the exposure is usually added thereto.
Many negative resist compositions using a phenol unit as an alkali-soluble unit constituting the polymer compound that can dissolve in an aqueous alkaline developer have been investigated for exposure especially with KrF excimer laser beam. These negative resist compositions have not been used for ArF excimer laser beam because the phenol unit has no transmittance to an exposure light with a wavelength of 150 to 220 nm. However, they have recently received a growing technical attention as negative resist compositions for EB and EUV exposure, which are used in an exposure method for forming a finer pattern, and examples thereof are proposed in Patent Documents 1, 2 and 3 as resist compositions that exhibit very high resolution even when the compositions are used for forming a thin film.
In addition to the above compositions, many materials have been investigated for the chemically amplified negative resist. For example, many crosslinking agents have been investigated to insolubilize an alkali-soluble polymer used in the resist composition that provides the negative mechanism by an effect of acid generated at the irradiation with a high energy beam, as used in Patent Documents 1, 2 and 3. On the other hand, there are various attempts to make a polymer having a function of crosslinking agent, and the following methods have been proposed: a method of introducing a styrene unit substituted with an alkoxymethoxy group (Patent Document 4); a method of introducing a repeating unit having an alkoxymethylamino group (Patent Document 5); a method of introducing a repeating unit having an epoxy group (Patent Document 6); a method of introducing a styrene repeating unit having an acid-labile group (Patent Document 7); a method of introducing an adamantyl repeating unit having an acid-labile hydroxyl group (Patent Document 8); a method of introducing an aliphatic hydrocarbon or alicyclic hydrocarbon repeating unit having an acid-labile hydroxyl group (Patent Documents 9, 10, and 11). Examples of the materials having an acid-labile hydroxyl group are proposed in Non-Patent Documents 1, 2, and 3.